IRS Flashcards
How are the IRU’s normally powered?
AC power
Hot battery bus as backup power
What is the priority for inputting IRU position
- GPS
- Last known position
- Airport position
- Parking position
On the ADI/HSI what displays are produced by the IRU’s?
Heading
Attitude
Wind
Position
Track
Ground Speed
Trend Vector
VSI
During the alignment process of the IRU’s, what lights are displayed?
ON DC – first displayed
When powered they go to steady white align light
On the ground, selecting HDG does what?
Gives the minutes remaining for IRU alignment
How does it take for an IRU to align?
10 minutes
Quicker closer to the equator
Selecting HDG will never show more than 7 minutes. Even if it is
When is a high latitude alignment required?
Somewhere near the 70’s
Supplemental procedures may be required
If the nav selector is moved out of nav due to a non normal procedure in flight, what happens?
Must be confirmed as a pilot team
IRU lost for navigation
Follow supplemental procedures
Why might the map move when selecting the thrust button on takeoff?
IRU is updating position
What is the logic for the IRU position update?
Still or steady state
AC power to the aircraft
All the selectors to NAV
Why is the ON DC light the first to illuminate?
Must check its ability to go to Hot battery bus power
If an IRU can’t go to the Hot battery bus DC FAIL is illuminated
What is the IRU Alignment process?
Selectors to NAV
ON DC Steady align
Steady white alignment light on
GPS selected in scratch pad
Alignment process
What happens upon alignment of the IRU’s?
Upon alignment of the first IRU the yaw damper INOP lights go off
EADI/EHSI providing infomraiton
What causes the align lights to blink?
Forget to enter position – turn IRU selectors to OFF and begin again
Wrong position entered
Moving the aircraft
(No Bad Move)
If moving the aircraft with an align light blinking. What sensors informs the IRU’s that the aircraft is moving?
Movement of the Wheel
Wheel sensors
